In the semiconductor industry, devices are fabricated by a number of manufacturing processes producing structures of an ever-decreasing size. Some manufacturing processes such as plasma etch and plasma clean processes expose a substrate to a high energy plasma to etch or clean the substrate. The plasma may be highly corrosive, and may corrode processing chambers and other surfaces that are exposed to the plasma. This corrosion may generate particles, which frequently contaminate the substrate that is being processed, contributing to device defects.
As device geometries shrink, susceptibility to defects increases and particle and contaminant requirements become more stringent. Accordingly, as device geometries shrink, allowable levels of particle contamination may be reduced.
Many chamber components such as showerheads, plasma sources, pedestals and liners used in semiconductor etch and selective removal chambers are made of bare aluminum or anodized aluminum. However, when exposed to fluorine-based plasma these chamber components become fluorinated and cause particle contamination. Additionally, showerheads contain numerous holes through which gases are flowed. The diameter of these holes changes over time due to accumulation of fluoride particle buildup. The change in hole diameter causes process drift and etch-rate drift over time, which reduces the lifespan of the showerhead.